Evaluation of new strain (AAD16) of Beauveria bassiana recovered from Japanese rhinoceros beetle: Effects on three coleopteran insects.

A strain (AAD16) of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin was isolated from field-collected Japanese rhinoceros beetle, Allomyrina dichotoma (L.) (Coleoptera: Scarabaeidae). Its virulence was compared with another strain (ARP14) recovered from a cadaver of Riptortus pedestris (F.) (Hemiptera: Alydidae) focusing on its effect on three coleopteran, i.e., Tenebrio molitor L., A. dichotoma, and Monochamus alternatus Hope. The LT50 value of T. molitor for two larval sizes, i.e., 16-18 and 22-24 mm, was 15.3 and 19.4% lower for strain AAD16 compared to strain ARP14, respectively. Furthermore, after 8 and 10 days of exposure, the mycosis rate of strain AAD16 was 1.3 and 1.2 times higher than that of strain ARP14 in the 16-18 and 22-24 mm larval sizes, respectively. The LT50 for M. alternatus larvae was 23.2% lower on strain AAD16 than on strain ARP14. In addition, the LT50 for M. alternatus adults was 47.1% lower for strain AAD16 compared to control. The mycosis rate of strain AAD16 on M. alternatus larvae was 1.8 higher than that of strain ARP14 after 120 hours of exposure. The strain AAD16 also showed higher larval mortality (90%) for A. dichotoma compared to strain ARP14 (45.0%) at 28 days after exposure. These results suggest that B. bassiana AAD16 can be a potential biological control agent against coleopteran pests.